All those tanks sizes are way too small for balas and needlefish unfortunatly. The bala sharks will get too 12 inches and like to be in schools or at least pairs. And the needle fish will get bigger and meaner than the balas as well. You would probably need a 75-120 gallon to house them properly and safley, also because of the size you would need a good filtration system as well. Also most needlefish want feeding live food most of the time things like bugs or moths or krill or other shrimp etc.
If you got the 37 you could maybe to denison barbs? They are kind of like balas in their shape and scales but they have a bright red stripe down each side with yellow tails google them

For the 12 your really looking at dwarf gouramis, tetras, maybe cories, shrimp or a betta with tetras or rasboras? If you can get the 28 you could maybe get some dwarf new world cichlids like keyholes or any of the appistogrammas? Few ideas for you there

hope ive helped and sorry to tell you about them getting to big you seemed really set on them